Does a metal detector help find meteorites?
Yes, for iron meteorites and most ordinary chondrites, which contain iron-nickel metal. It won't detect metal-poor types such as many achondrites and carbonaceous chondrites, and natural magnetic rocks cause false signals.
A metal detector can be a powerful tool, especially for finding meteorites buried just below the surface, where your eyes cannot help. But it only works for some kinds, and it needs practice.
Detectors respond to conductive metal. Iron meteorites, made mostly of iron-nickel alloy, give strong signals and have been found by detectorists at considerable depths, such as in old strewn fields in the United States and Argentina. Most ordinary chondrites, the commonest stony meteorites, contain flakes of iron-nickel metal too: H chondrites have roughly 15 to 20 per cent metal by weight, L chondrites less and LL chondrites less still, so the signal weakens through the group. Small stones may give only a faint response.
Many important meteorites contain little or no metal. Most achondrites, such as howardites and other rocks from the asteroid Vesta, as well as Martian and lunar meteorites and many carbonaceous chondrites, are nearly invisible to a detector. Weathering also turns metal into rust, weakening the signal in old finds. The other problem is false alarms. Rocks rich in the mineral magnetite, or soils containing magnetic minerals, produce signals detectorists call hot rocks. Modern detectors have ground balance settings to cope with mineralised ground, and experienced hunters learn to recognise the tones. Many also carry a strong magnet to test each target quickly.
Before you switch on, check the rules. In many countries, including the UK, you need the landowner's permission to use a metal detector, and detecting on protected or historic sites is illegal. Laws vary from country to country, so research before you go. Fill in any holes you dig, and record the exact position of anything promising.